Diabetes is a life-style related disease derived from multiple causative factors. It is characterized by elevated levels of plasma glucose (hyperglycemia) in the fasting state or after administration of glucose during an oral glucose tolerance test. There are two generally recognized forms of diabetes: type 1 and type 2 diabetes mellitus. In type 1 diabetes, or insulin-dependent diabetes mellitus (IDDM), patients produce little or no insulin, the hormone which regulates glucose utilization. In type 2 diabetes, or noninsulin-dependent diabetes mellitus (T2DM), insulin is still produced in the body, and patients demonstrate resistance to the effects of insulin in stimulating glucose and lipid metabolism in the main insulin-sensitive tissues, namely, muscle, liver and adipose tissue. These patients often have normal levels of insulin, and may have hyperinsulinemia (elevated plasma insulin levels), as they compensate for the reduced effectiveness of insulin by secreting increased amounts of insulin.
The treatment of T2DM generally begins weight loss, healthy diet and exercise program. Although these factors are important especially to dissolve the increased risk of cardiovascular disorders related to diabetes mellitus, they are not effective generally for the control of diabetes mellitus itself. There are many drugs useful for the treatment of diabetes mellitus, including insulin, metformin, sulfonylureas, acarbose, thiazolidinedione, GLP-1 analogue and DPP IV inhibitor. There are, however deficiencies associated with currently available treatment, including hypoglycemic episodes, weight gain, loss in responsiveness to therapy over time, gastrointestinal problems, and edema.
Although a number of receptor classes exist in humans, by far the most abundant and therapeutically relevant is represented by the G protein-coupled receptor (GPCR) class, it is estimated that approximately 4% of the protein-coding genome encodes GPCRs. GPCRs are also known as seven-transmembrane domain receptors as they share a common structural motif, having seven sequences of between 22 to 24 hydrophobic amino acids that form seven alpha helices, each of which spans the membrane. Further, there has been renewed focus on pancreatic islet-based insulin secretion that is controlled by glucose-dependent insulin secretion (GDIS). In this regard, several orphan G-protein coupled receptors (GPCR's) have recently been identified that are preferentially expressed in the β-cell and are implicated in GDIS.
GPR119 is a cell-surface GPCR that is highly expressed in human (and rodent) islets as well as in insulin-secreting cell lines. Activation of GPR119 has been demonstrated to stimulate intracellular cAMP and lead to glucose dependent GLP-1 and insulin secretion (T. Soga et al Biochem. Biophys. Res. Commun. 2005, 326). Synthetic GPR119 agonists augment the release of insulin from isolated static mouse islets only under conditions of elevated glucose, and improve glucose tolerance in diabetic mice and diet-induced obese (DIO) C57/B6 mice without causing hypoglycemia.
There still remains a need for alternative novel synthetic compounds which acts as GPR119 agonists and are useful in the treatment and prevention of metabolic disorders, including diabetes mellitus (type I and type II), and related disorders.